Electrical measuring instrument.



' R. .9. BROWN. BLBGTBIGALFMEASUBING INSTRUMENT.

APPLICATION FILED EB. 12, 1913.

1,105,481. Patented July 28.1914

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nicann'rl-lnnovvivfj'orf PiaILiiELrnIA, PENNSYLVANIA, AssIeNoB. To KsYs'roNn ccsronArIoN or ri:,NNs'YrlvANIAt anacreican, :Nsrnuainnr COMPANY,

incensi;

To all whom, it may concern: .v

Be Vit known that I,-R1CHARDVP. BROWN.,A a citizen ofthe United States, and a ,resin dent of the city and county of Philadelphia, State of Pennsylvania, have inventedcertain new and useful Improvements in Electrical Measuring Instruments, of which the following is a specification.

My invention relates to improvements in electrical measuring instruments and more particularly to improvements in that class of instrument which comprises a permanent magnet, a core placed between the poles or pole pieces of the magnet, a moving coil surrounding the core and a pointer actuated b v the movements of the moving coil and indicating, in connection with a suitable scale, the electric current flowing through thecoil.

Briefly the operation of the instrument is that of the well known Deprey DArsonval galvanometer but as this invention relates more particularly toan improved means for carrying the core which will permit its removal from, or insertion between, the poles or pole pieces of the magnet without there being any possibilityof the core or the moving coil engaging the magnet it will be unnecessary to herein particularly describe the operation of the machine or to enter into any description of its purposes or operation. As the poles and po e pieces of a magnet are, for the purposes of my invention, substantially identical I will hereinafter refer to them as the poles it being understood that by this term I intend to inelude both constructions.

My invention is illustrated in the accom-` panying drawings which form part of this .specification and in which similar numerals of reference indicate similar parts throughout the several views.

In these drawings Figure 1- is a front view of a galvanometer embodying my invention, the core and carrying bracket being shown in section: Fig. 2-- a section of Fig. 1 on line A-A: Fig. 3- a perspective view of the pole pieces of a magnet and of part of a core carrying bracket car- 'i ried by the tips of opposite polesof the magnet.

l is a permanent magnet, 2 the ypoles'or pole pieeesiofthe magnet, 3 a coresurrounded by a movingv coil 4 which actuates'l l Specification of Letters Patent.. -5 Applicationrlediebrnary 1.2, 1918. Serial No. 747,907.

F PHI*LAI)ELLPHIVA,, PENNSYLVANIA, A

ntncfrnical, MEAsnRING INSTRUMENT.

Patented July es, isla.

anpointer 5 which indicates, when the instrument. is properly calibrated, upon a scale the current passing through it.

6 is a bracket which carries the core, which latter, more 0r less frequently, for cleaning, for repairs or when the instrument is being assembled, has to bc removed from between the poles of the magnet and unless some means be provided for guiding the core while being inserted or Withdrawn, the attraction of the magnet will draw the core against one or the other of the poles to the injury of the moving coil 4 which surrounds the core which is necessarily of more or less delicate construction.

My arrangement for guiding the core in inserting or withdrawing it is as follows: The bracket 6 of non-magnetic material, which carries the core 3, and which is furnished with arms 7 for carrying the pivots 8 carried by the moving coil 4 1n the usual manner, is` upon its opposite sides longitudinally grooved as at 9 9, these Igrooves are adapted to slide over the tips 10 of the polesl of the magnetvvhich form stationary guides. The core, the moving coil, the pointer and the other parts of the instrument secured to or forming parts of these lseveral pieces are all carried by the bracket 6 and hence when this latter is moved in or out upon the tips of the poles as guides these parts are moved along with it and so long as the grooves 9 in the bracket are engaged by the tips of the poles, it is impossible for the core, or any of the other parts, to be moved out of central alinement between the poles. The space between the core and the poles of the magnet is necessarily small, this is still further reduced by the moving coil which surrounds the core and in this restricted space dust may collect which makes a removal of the core and its connected parts necessary for purposes'of cleaning. It is principally for this that my invention is intended but the construction is, of course, equally useful in preventing contact of the parts in initially assembling the instrumentor in taking it down to etiect repairs.

,A `The invention is, of course, applicable to claim as nevi-.and desire to secure by Letters a core which is partially sui-rounded by the Patent l. The Vcombination with a magnet and a core which is partially surrounded by the poles of said magnet, of a bar or bracket of non-magnetic material secured longitudinally to said core and adapted te' be slidabl-y engaged and carried by adjdcent opposite tips of the pole pieces of said 10 magnet.

poles of said magnetfof a. bracket of new magnetic material for carrying said core the opposite sides of which are longitudinally grooved and adapted to engage the tips of the poles of the magnet.A

RICHARD P. BROWN;

Witnesses GEORGE W. W. CORNMAN, lJOHN P. GOHEEN, 

